limx→1x3-x2x-1=limx→1x2=1,
故选B.
What will the speaker probably talk about next().
A.Cases of physical or sexual abuse.
B.Types of abusive parents.
C.Consequences of child abuse.
D.Laws against child abuse.
将塑料梳子接入闭合电路中,小灯泡不发光,说明塑料梳子是________.用这种梳子梳干燥的头发时,头发会随梳子“飘”起来,这是因为________________________________.